Broadband circularly polarized aperture coupled L-band patch antenna for airborne applications

Microstrip antennas are no longer considered narrow band and improvements in bandwidth are frequently reported. These improvements also increase their areas of applications. Circular polarization is preferred for airborne applications and though lightweight, microstrip antennas have limitation in achieving circular polarization bandwidth. Here, a multi-layer microstrip patch antenna design is presented in L-band, wherein a very broadband circular polarization performance is reported. The compact arrangement consists of an aperture coupled patch with a parallel-fed crossed slot coupling using Wilkinson's power divider and 900 extra line length in each branch. The performance achieved includes a 10 dB return loss over 40% bandwidth, a 3-dB axial ratio bandwidth of 34% and 4 dBi gain bandwidth over 32%. The design and performance details are described in the. paper.